Houston is the 4th largest city in the US, and has the 8th highest HIV rate in the country. In the past 29 years since the first AIDS case was reported in Houston, rates of HIV infection have remained high, especially among minority populations. The three main at-risk populations are men who have sex with men (MSM), injection drug users (IDU), and heterosexuals living in areas of high HIV prevalence (HET). Houston is directly funded for HIV prevention through the CDC, and has a responsibility to monitor the HIV epidemic through behavioral surveillance. For the past seven years Houston has been part of the National HIV Behavioral Surveillance (NHBS) project. Such surveillance is important to ensure that HIV prevention functions address the appropriate behaviors among the highest risk populations, and that prevention efforts have the desired effect of changing risky behaviors that place people at increased risk of HIV. The specific aims of our study are to develop an ongoing HIV behavioral surveillance program designed to: 1) ascertain the prevalence of, and trends in, HIV risk behaviors among MSM, IDUs, heterosexuals at risk for HIV infection and male to female transgender individuals (TG);2) describe the seroprevalence of HIV in all populations, and the seroprevalence of HCV among the IDU population, and 3) to assess the access to, and utilization of, HIV prevention services and HIV testing among these high risk populations. Participants will be recruited using venue-based sampling for the MSM cycles and respondent driven sampling for the IDU, HET and TG cycles. We will use the standardized NHBS protocol and core questionnaire;additional information will be collected about local prevention programs. Voluntary rapid HIV testing will be offered to determine the seroprevalence of HIV among the target populations. Additional Hepatitis C testing will be offered to IDU population. Data collected from NHBS will be used to describe trends in key behavioral risk indicators and evaluate current HIV prevention programs. This information can be used to identify gaps in prevention services and target new prevention activities with the goal of reducing new HIV infections in Houston.